BAGHDAD (AP) — Islamic State group militants shot down an Iraqi military helicopter, officials said Saturday, killing the two pilots onboard and raising fresh concerns about the extremists' ability to attack aircraft amid ongoing U.S.-led coalition airstrikes.

The attack happened late Friday in the Shiite holy city of Samarra, about 95 kilometers (60 miles) north of Baghdad. A senior Defense Ministry official told The Associated Press the Sunni militants used a shoulder-fired rocket launcher to shoot down the EC635 helicopter on the outskirts of the city.

An army official corroborated the information. Both spoke on condition of anonymity as they weren't authorized to speak to journalists.

The EC635, built by Airbus Helicopters, is used for transportation, surveillance and combat.

The militants shot down at least two other Iraqi military helicopters near the city of Beiji in October. Some fear the militants may have captured ground-to-air missiles capable of shooting down airplanes when they overran Iraqi and Syrian army bases this summer.

European airlines including Virgin Atlantic, KLM and Air France, U.S. carrier Delta Air Lines and Dubai-based Emirates changed their commercial flight plans over the summer to avoid Iraqi airspace.

The Islamic State group holds about a third of Iraq and neighboring Syria in its self-styled caliphate.

In Syria, meanwhile, an activist group and a jihadi website said the Islamic State group's police force beheaded four men in the central province of Homs for insulting God.

The Britain-based Syrian Observatory for Human Rights said the four were beheaded Friday in the province's east, without elaborating.

A jihadi website said the "Islamic police in the state of Homs" carried out a court sentence against the four in the presences of onlookers. Grisly photos posted on the website showed each of the four blindfolded men kneeling, their hands tied behind their backs, as a masked man in a black uniform hit their necks with a cleaver.

The Islamic State group governs its territory according to its radical, violent interpretation of Shariah law. It has carried out other mass killings and beheadings, often recorded and posted online.